The MissionThe Mission

Explore the Dark Ages through the neutral hydrogen distribution

Constrain the populations of the first stars and first black holes.

Measure density fluctuations in the early universe

Obtain the equation of state of dark energy test alternate theories of gravity

[The first 4 slides are taken from Greg Taylor’s presentation on telescope requirements to LARC/DALI meeting at GSFC in Jan 2009]

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Assumptions Assumptions

Array to be located on the Far Side of the Moon Minimizes terrestrial RFI Minimizes Ionospheric Fluctuations

Observe during the Lunar night (50% duty cycle) Minimizes solar RFI

Array to consist of N stations, each with M dipole pairs

Each station will be capable for forming B beams on the sky

Array assumed to be deployed in a locally flat region

Array is to be deployed robotically

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Scientific Requirements Scientific requirements Redshift range: z=50 to 6 Angular resolution: 1.4’ Bandwidth: 8 MHz Sensitivity in 1000 h at z=15:

0.2 microJy/beam Brightness Sensitivity: 4 milliK FOV: 11 sq deg Dual Circular Dynamic range: 106 to 107

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Technical Requirements Technical requirements Frequency range: 30 - 200 MHz Collecting area: 3.0 km2

Maximum baseline: 10 km Bandwidth: 8 MHz Station Diameter: 150 m

Number of Stations: 300 Number of Beams: 9 Dipole pairs in each station: 1500

Antenna FOV: 45 deg FWHM

Ground-based reionization experiments

Science Goals of the Murchison Widefield Array

• Epoch of Reionization• Heliospheric Physics• Astronomical transients

Sited in Western AustraliaMIT Haystack Observatory

MIT Kavli InstituteHarvard-Smithsonian Center for AstrophysicsAustralia National UniversityMelbourne University + consortiumRaman Research Institute

Chippendale & Beresford 2007

Antenna tile 32 antenna tiles

26-tile MWA image Simulation

Imaging by R. Wayth

Current Phase is MWA “Demonstrator”(under construction)

N=512; D=4m - LARGE etendue; good foreground subtraction

Digitized at antenna (660 Msamples/sec) - direct conversion

Raw data rate = 512 X 2 X 660MHz X 10 bits = 844 GB/sec

After digital filters and correlator: 20 GB/sec (32 MHz bandwidth; 2 Gvis per half-second)

Real-time antenna and ionosphere calibration every 8 seconds

Map of antenna tile field of view (~30 degrees across) every 8 seconds

Status: 32 tiles on site; currently taking data with 26 tiles

Reionization spatial power spectrum

Bowman, Morales & Hewitt (2006)

MWA power spectrum sensitivity (in principle) at redshift 8

• Focus: Reionization (power spec,CSS,abs)

• Very wide field: 30deg

C.Carilli, A. Datta (NRAO/SOC), J. Aguirre, D. Jacobs (U.Penn)

PAPER: Staged Engineering• Broad band sleeve dipole + flaps

• FPGA-based ‘pocket correlator’ from Berkeley wireless lab, routing via switch

• S/W Imaging, calibration, PS analysis: AIPY, including ionospheric ‘peeling’ calibration, W projection…

100MHz 200MHz

BEE2: 5 FPGAs, 500 Gops/s

150 MHz PWA-4/PGB-8

Powerspectrum

Antenna Development for LUNAR (Bradley NRAO)

Optimize the electromagnetic behavior of the four-element helical array through parametric modeling.

Study effects of lunar deployment tolerances.

Develop a viable mechanical design for the low-mass, folding antenna truss structure.

Build prototypes for operation at 137 MHz and determine beam patterns by measuring the downlink power from a constellation of LEO satellites.

LARC Concept of the Lunar Radio Array

Notional design completed as part of NASA Award NNX08AM30G

The Self-Tending Array Node and Communications Element

-- STANCE --

Quad helical antennas, grounding cavity, and folding support truss adopted as the baseline design.

NRAO Statement of Work: Software requirements

Years 3 + 4: half-time postdoc position will be used to study the software requirements for the lunar array to detection the cosmological HI 21cm singal. Funding for the other-half time is being sought within the NRAO algorithms development group. Goals:

1. Report on telescope software requirement, based on science requirements and design, summarizing processing and analysis software requirements.

2. A report reviewing the current software being written for low frequency ground-based arrays, making recommendations as to aspects of these systems that can be incorporated into the Lunar software design.

3. If time allows, explore low frequency data processing using data from existing low frequency instruments.